In the design of printed circuit boards for use in electronic equipment, it is often desirable to increase the component carrying capacity of a particular board for circuit function considerations. For example, a memory cluster is available commercially from one particular semiconductor manufacturer. The component consists of a plurality of memory integrated circuit packages clustered on a relatively small printed circuit board which is pluggable in a connector mounted on a motherboard.
In telecommunication systems such as telephone switching systems, it is also desirable to use appendage circuits or daughterboards mounted on printed circuit boards of the system. For example, some types of line circuits are realized using a thick film hybrid circuit which is configured separately on its own substrate. The substrate is provided with a plurality of pins suitable for insertion into cooperating mounting holes in the motherboard. Hence, the hybrid circuit substrate is treated as a conventional component.
A problem associated with the mounting of hybrid substrates on printed circuit boards is that they consume considerable shelf space since the lateral inter-spacing of printed circuit boards along a shelf of equipment must allow for the height of the daughterboards mounted on the boards. The problem may be solved by mounting the daughterboard flat on the motherboard with the mounting pins bent at a right angle thereinto. However, this solution tends to be impracticable in that it results in the consumption of the very printed circuit board real estate savings realized through the use of a daughterboard. The mounting of a hybrid circuit or the like at an angle other than horizontal or orthogonal to the motherboard is usually not workable because the weight of the circuit may cause its connecting pins to work free or to be stressed to the point of breaking or separating from the circuit.
Another solution to the problem of mounting a daughterboard on a motherboard have been to use stand-offs and a wiring harness between the boards. Yet another method is to use a connector into which the daughterboard may be plugged. Both of these solutions are impractical in that they are expensive or awkward to implement in the manufacturing process.
The invention solves the above-discussed problem of mounting a thick film hybrid circuit on a motherboard in a very economical manner that allows the motherboards's lateral shelf space to be minimized.